51. Solving a chemistry problem

176. A weighing of 1.000 g of ammonium salt was treated with an excess of concentrated NaOH solution. The released ammonia was taken up with 50.00 ml of a 1.072 M HCl solution and the excess acid was titrated with 25.40 ml of NaOH (ТNaOH = 0.004120 g/ml). Calculate the mass fraction (in %) of NH3 in the sample.